One possibility is to take SEPTA and/or NJT to Seacaucus Jct., then the Port Jervis line to Port Jervis and then ride back to the Trenton or Philly area. You can do it camping or via motels. The ride through the Delaware Water Gap National Recreation Area is wonderful. Once you get to Lambertville you can either stay on the D&R feeder canal trail to Trenton or cross into PA and take roads to Philly. There is also a trail on the PA side, but I am not sure where it takes you south of New Hope. This is easily doable in 3 days. Recommended itinerary if camping is Port Jervis to Worthington State Forest campground, Worthington to Dog Wood Haven campground in Upper Black Eddy, Dog Wood Haven to either Philly or Trenton. There is also an option to skip Worthington and instead camp next to and then the next day visit the Lakota Wolf Preserve in Columbia, PA. The only SNAFU is that you would have to take the train trip to Port Jervis on Saturday or Sunday. That's because NJT changed its NEC schedule a few years back. Now, with the weekday bike on train restrictions, it's not possible to make the connection with the last morning train to Port Jervis, and the afternoon/evening trains in that direction do not allow bikes. Each time I have done that trip I have rented a car one way and dropped it off in Port Jervis. Avis has a one-way drop off location there in town.